Direct current motors are commonly used in vehicle engine cooling systems to drive, for example, and engine cooling fan. In the event a dc motor is stalled, for example if some foreign object is blocking the fan wheel or the motor, some form of blocked rotor protection is required from damaging the motor or wiring harness. Without stall protection, it is possible for electrical damage or even fire to occur from overheating of the motor.
Accordingly, there is a need to provide blocked rotor or stall protection both at motor start up and during motor operation no matter how the motor is operating (e.g., PWM mode or dc mode).